1. Field of the Invention
The present invention relates in general to a method and apparatus for making secure a hydraulic gang connector in remote or hazardous locations. More particularly, the invention relates to a method and apparatus for the simultaneous connection and disconnection of multiple male and female couplers to provide sealed conduits for subsea operations.
2. Description of the Related Art
Subsea oil and gas production equipment that requires the use of external signals or the supply of fluids for operation is normally connected subsea after installation with interconnecting cables, jumpers, or umbilicals having removable connectors on each end. Remotely Operated Vehicles (“ROVs”) are normally used to connect the removable (outboard) connector to the fixed (inboard) connector on the subsea equipment. Due to operational conditions (such as ROV size and strength, weight of connectors, ocean currents and drag induced by pulling the cables across the seafloor), proper alignment of the removable and fixed connectors can be difficult and time consuming, and improper alignment can damage the components of the fixed and/or removable connectors.
There are three important aspects of connector design: alignment, latching and protection of components. The first requirement (alignment) is to get the fixed and removable connectors aligned quickly and accurately. The second requirement (latching) is to latch the fixed and removable connectors together such that they form a watertight seal with each other. The third requirement (protection) is to protect tubing and other components during storage, handling, transport and installation operations.
There are many alignment schemes currently used in subsea operations. A typical method is to insert a stepped pin into a cylinder having a leading chamfer. As the pin enters the cylindrical receptacle at some entry angle, the pin generates a force that causes it to align with the receptacle. Two pins are required to get alignment in two planes.
Another alignment method used is a cylinder with a symmetrical, outwardly expanding internal notch having 180 degree helical sides extending to its opening end such that a comating pin having a complementary radially outwardly projecting helix, round pin, or other protrusion may be inserted. Engagement of the female helical surface with the male helical surface, the pin, or the can provide up to 180 degrees of rotational alignment in either direction, but the mechanism is long and requires a high axial force to achieve alignment.
There are also many latching methods in use for securing the removable connector to the fixed connector. The removable connector is normally carried and installed by the ROV with the use of an industry standard torque tool and a flying lead orientation tool (“FLOT”). The usage of the torque tool as a standard practice requires the connector designs to include some kind of threads. The earliest methods relied on remotely engaging a male and female thread subsea and required much care not to cross-thread the connection. Cross-threading usually requires retrieval of the subsea equipment to repair the damaged thread on the fixed connector.
A preferred latching method is to use permanently engaged threads on the removable connector with a latching profile that engages the fixed connector. One type of profile currently used is a collet latching onto a fixed hub. This is a common method for making large diameter connections for use in pipelines and wellheads. This concept is compact and works well to pull the halves together but when the operation takes place in deep water where the force to separate the plates is large, the fingers of the collet are susceptible to buckling. The override of this type of connector requires the use of a hydraulic ram to pull a sleeve that captures the collet back thus releasing the collet.
In 1982, Exxon patented (U.S. Pat. No. 4,362,413) a method in which the threads are permanently engaged. This method relied on inserting a nut with an external profile into a receptacle and turning the nut 90 degrees until a mechanical stop prevented the nut from rotating any further and restrained the nut axially. A disadvantage to this concept is that the size of the receptacle used in the connector relative to the thread size is not very efficient for designs concerned with size and weight.
Two other concepts that are similar to the Exxon patent are the Oceaneering patent by Cunningham (U.S. Pat. No. 5,794,701) and the pending Subsea 7 patent by Glennie (U.S. patent application Ser. No. 10/477,088) that is in Re-Examination. The Oceaneering patent discloses a specific configuration of components based on the engagement of a receptacle on the fixed connector and a stud with lugs or profiles on the removable connector. The Subsea 7 patent application is based on the same concept but also covers an override feature utilizing shear pins.
A similar latching mechanism is also used by Intec Engineering, which is based on the Retlock concept acquired from Fuel Subsea. The Intec Engineering system is the DMAC or Diverless Maintained Cluster that is also marketed by Subsea 7.
Bayonet-type latching systems have the latch pin mounted on the face of the removable connector and the latch sleeve mounted in the fixed connector. This design leaves the latch pin exposed to damage from storage, handling, transport and installation of the removable connector.
All of the above-described designs leave the tubing exposed to damage from handling and ROV operations, are susceptible to thread damage and are difficult to align, thereby increasing the probability of damaged tubing or other components during installation.
There exists a need for an apparatus and method that provides both a coarse alignment and a fine alignment that is easy and quick to execute.
There is a further need to provide a connector with an apparatus and method of latching the parts of the connector together without the need for engaging threads subsea.
Furthermore, a need exists for providing a connector design that provides the desired alignment and latching characteristics, while providing a protection mechanism for the tubing, latching system and other components of the subsea connector system.